Listen for 8 minutes ahead.
The same distorted sound came out of the headphones during recording.
The fault was the same with Line in or Q4n's own microphones.
The fault was the same with the manual recording level -12 dB or Autogain.

The memory card was 64GB of Sandisk with 54GB of videos and about 8GB of space.

Is the appliance broken? It's only a few hours spent. Is the other Q4N the same fault?

This has been resolved. Q4N is not broken, but it is a delicate mobile phone for radio broadcasting.
Q4N near was Facebok live broadcast tablet mobile radio broadcast operation.
The other cameras are not so sensitive.
The security distance must be 2 meters with Q4N!!!